Firefighters clean equipment on Second Street after dousing a suspicious fire below the University Avenue overpass in Berkeley, Calif. on Wednesday, May 7, 2014. The cause of the blaze, which snarled traffic on the freeway and surface streets, is under investigation.

Burned and melted bins and foam on the ground are seen in an area where a fire broke out below the University Avenue overpass on Wednesday, May 7, 2014 in Berkeley, Calif. The cause of the fire is under investigation.

Berkeley police officers take a man into custody after a suspicious fire broke out below the University Avenue overpass at the eastbound I-80 off-ramp in Berkeley, Calif. on Wednesday, May 7, 2014. The cause of the blaze, which snarled traffic on the freeway and surface streets, is under investigation.

Berkeley police officers take a man into custody after a suspicious...

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Police officers block access to Second Street as fire officials investigate a fire that broke out below the University Avenue overpass in Berkeley, Calif. on Wednesday, May 7, 2014. The cause of the blaze, which snarled traffic on the freeway and surface streets, is under investigation.

A Berkeley police officer questions a man after a suspicious fire broke out below the University Avenue overpass at the eastbound I-80 off-ramp in Berkeley, Calif. on Wednesday, May 7, 2014. The cause of the blaze, which snarled traffic on the freeway and surface streets, is under investigation.

Berkeley police officers detain a man after a suspicious fire broke out below the University Avenue overpass at the eastbound I-80 off-ramp in Berkeley, Calif. on Wednesday, May 7, 2014. The cause of the blaze, which snarled traffic on the freeway and surface streets, is under investigation.

A Berkeley police officer questions a man (far right) after a suspicious fire broke out below the University Avenue overpass at the eastbound I-80 off-ramp in Berkeley, Calif. on Wednesday, May 7, 2014. The cause of the blaze, which snarled traffic on the freeway and surface streets, is under investigation.

Police and fire officials investigate a suspicious fire that broke out below the University Avenue overpass at the eastbound I-80 off-ramp in Berkeley, Calif. on Wednesday, May 7, 2014. The cause of the blaze, which snarled traffic on the freeway and surface streets, is under investigation.

Berkeley police chief Michael Meehan walks up a pathway next to the University Avenue overpass under which a fire broke out on Wednesday, May 7, 2014 in Berkeley, Calif. The cause of the fire is under investigation.

The blast was reported about 2:40 p.m. underneath the University Avenue overpass to Interstate 80.

The fire was controlled within 20 minutes, said Berkeley Fire Chief Gil Dong. Thick black smoke could be seen for miles.

A person near the fire scene was treated for minor injuries and released, said Officer Jennifer Coats, a Berkeley police spokeswoman. Two people found near the scene were detained as part of the investigation and released, she said.

Firefighters had received reports that the blast could have been related to a clandestine methamphetamine lab, but no signs of a drug lab were found at the scene, Dong said. The cause of the fire is under investigation.

The California Highway Patrol closed the University Avenue off-ramp from eastbound I-80 as firefighters doused the blaze.